(a) Each imperfection or damage that impairs the serviceability of a segment of steel transmission line, or distribution main operating at 125 psig (860 kPa) or more in a Class 3 or 4 location, must be repaired according to the following requirements.
(1) If it is feasible to take the segment out of service, the imperfection or damage must be removed by cutting out a cylindrical piece of pipe and replacing it with pipe of similar or greater design strength.
(2) If it is not feasible to take the segment out of service, the imperfection or damage must be repaired by a method that reliable engineering tests and analyses show can permanently restore the serviceability of the pipe.
(b) If the segment is not taken out of service, the operating pressure must be reduced to a safe level during the repair operations.